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Astronomy – The Week Ahead: Sun 1 Feb thru Sat 7 Feb

Tonight features two planets. Venus is at 23.8° E of the sun, brilliant in the western sky, outshining Mars nearby in Aquarius. On the eastern horizon Jupiter is rising almost concurrent with sunset. Its moon Io is showing a Shadow Transit as it rises. It will end at 19:15. You can watch the black spot approach and then leave the limb of Jupiter, followed seven minutes later by Io itself. But keep watching, as Io moves off the planet and Europa swings toward the backside into an eclipse. The fun part is that Io and Europa will “merge” as Io passes in front, just as Europa disappears into Jupiter’s shadow at 19:32!

Monday February 2

The Summer Triangle, comprised of Deneb, Vega and Altair, are up in the east before sunrise. This famous asterism is easy to see, with Altair directly over the eastern horizon. Look for the Milky Way: it stretches most obviously through Cygnus, Aquila and Scutum. Many people mistake it for clouds over the horizon.

Tuesday February 3

Today is February’s Full Moon arriving at 6:09 pm eastern time. It is called Full Snow Moon or Full Hunger Moon by Native American tribes, for the year’s heaviest snow and difficulty hunting.

Other Native American tribes called this Moon the “Shoulder to Shoulder Around the Fire Moon” (Wishram Native Americans), the “No Snow in the Trails Moon” (Zuni Native Americans), and the “Bone Moon” (Cherokee Native Americans). The Bone Moon meant that there was so little food that people gnawed on bones and ate bone marrow soup.

The Moon will be paired nicely with Jupiter, between Leo and Cancer, both rising within minutes of each other. The Moon will be in the sky all night, Jupiter, almost all night.

Moon Fact: 2,160 miles in diameter, less than the width of the United States.

Wednesday February 4

Epsilon Lyrae is a famous multiple star system, 161 light years from us in the constellation Lyra. It is commonly referred to as The Double Double, since it is comprised of a pair of double stars in close proximity to each other.

The un-split pairs shine at a combined magnitude 4.5, so they are easy to see near Lyra’s bright star Vega. Sharp eyes in excellent conditions can split the main pair into two stars 3.5 arc-minutes apart. Through a telescope, those two split each into their own, with separations of 2.3 and 2.6 arc seconds.

Thursday February 5

The Moon forms a nice pair with Leo’s brightest star Regulus all night and through sunrise today, with Jupiter nearby. The Moon is at apogee today, 406,200 km from earth. Apogee is the farthest point the Moon reaches in its lunar monthly orbit around the earth. A Full Moon at apogee is the opposite of the recently popularized “Super Moon”. Maybe we should coin the term “Mini-Moon” to describe this? Today’s moon is not full, but at a 16.2-day-old waning gibbous phase, 98% illuminated.

Friday February 6

Jupiter is at opposition today. Opposition is an astronomical term that means the Earth is directly between the Sun and a planet. This can only occur with the outer planets. Inner planets have conjunctions, both inferior and superior.

We are at our closest point to Jupiter for 2015, so is at it largest size for the year today at 45 arc-seconds. Since Jupiter is opposite us from the sun today, it will rise exactly at sunset, and set exactly at sunrise.

Saturday February 7

Gemini is up nicely early in the evening, giving us a great opportunity to enjoy views of the Eskimo Nebula, NGC 2392. While telescopes will not show the clarity of this image, a double shell structure and darker inner ring can clearly be seen around a 9th magnitude central star. In a low power view, note the color difference between the “fuzzy star” and the neighboring 8th magnitude star. See a greenish tint? This is a planetary nebula, a star blowing off layers of atmosphere toward the end of its life. NGC 2392 shines at magnitude 10, subtends 42 arc-seconds (the size of Jupiter), and is over 2870 light years away.